Sensorized brake pad calibration machines, systems, and methods

ABSTRACT

Various machines, systems, and methods for generating calibration data for a sensorized brake pad are disclosed. In some embodiments, a system includes a fixture, a brake pad retainer, a pressure plate, an actuator and a controller. The actuator applies a pressure to the sensorized brake pad and signals from the pressure sensors are received. Calibration data is generated based on the signals received from the pressures sensors when the pressure is applied to the sensorized brake pad.

CROSS REFERENCE

This application claims the benefit under 35 U.S.C. § 119 of ItalianPatent Application No. 102017000073192, filed Jun. 29, 2017, theentirety of which is incorporated by reference herein.

BACKGROUND Field

The present disclosure relates to machines, systems, and methods fordetermining calibration data, such as for determining calibration datafor a sensorized brake pad for use on a vehicle.

Description of Certain Related Art

A braking unit is a mechanical apparatus that diverts energy from amoving system, thereby reducing the motion of the moving system. Abraking unit is typically used for slowing or stopping a moving vehicle,such as by friction between a generally non-rotating brake pad and arotating brake disk or drum. The brake pad can be pressed against thebrake disk or drum by a brake caliper.

SUMMARY OF CERTAIN FEATURES

Some braking units include sensorized brake pads. Typically, sensorizedbrake pads include sensors, such as pressure sensors. This can enablethe brake pad to detect and/or measure the pressure and forces appliedto the brake pad while it is installed on the vehicle. Sensorized brakepads can allow the vehicle to detect conditions that may cause abnormalwear, noise and/or vibration.

Due to manufacturing variances in the sensors and/or the brake pad, thesignal outputs from the sensors may vary slightly between identicallymanufactured brake pads. In some configurations, to accommodate for thevariance between identically manufactured brake pads, the vehicle isprovided with calibration data in order to calibrate the vehicle to theinstalled brake pads such that the vehicle may accurately interpret thesignal outputs from the sensors. A need exists for determiningcalibration data for each brake pad and for the providing and use ofsuch data.

Various embodiments disclosed herein relate to a machine for determiningcalibration data for a sensorized brake pad. The sensorized brake padcan include pressure sensors that are configured to detect pressureapplied to friction material of the sensorized brake pad. The machinecan include a fixture. The machine can include a brake pad retainer. Theretainer can be supported by the fixture and configured to hold thesensorized brake pad fixed relative to the fixture. The machine caninclude a pressure plate. The pressure plate can be configured tocontact the friction material of the sensorized brake pad. The machinecan include an actuator. The actuator can be supported by the fixture ata first end and connected to the pressure plate at a second end.

The machine can include a controller. The controller can have anactuator control portion configured to control the actuator. Theactuator control portion can direct the actuator to apply a pressure tothe pressure plate such that the sensorized brake pad is compressedbetween the pressure plate and the brake pad retainer. The controllercan have a pressure sensor signal receiving portion. The pressure sensorsignal receiving portion can be configured to receive the signals fromthe pressure sensors when the pressure is applied to the sensorizedbrake pad. The controller can have a calibration data generator that isconfigured to generate calibration data, such as based on the signalsreceived from the pressure sensors when the pressure is applied to thesensorized brake pad.

In some embodiments, the actuator is positioned at an angle relative toa rotor-contacting surface such that pressure applied to the sensorizedbrake pad includes a normal force component and a shear (also calledtangential) force component. In some embodiments, the angle isadjustable. In some embodiments, the angle is adjustable preferablywithin a range of 50-80 degrees.

In certain embodiments, the machine further comprises a plurality ofactuators connected to the pressure plate and configured to applypressure to the pressure plate, wherein a normal force actuator isconfigured to apply a normal force component and a shear force actuatoris configured to apply a shear force component. In some embodiments, themachine further comprises a bearing that connects the normal forceactuator and the pressure plate. In some embodiments, the actuatorcontrol portion applies a plurality of pressures of varying magnitude tothe sensorized brake pad. In some embodiments, the plurality ofpressures range in magnitude between 1-150 bars.

In certain embodiments, the machine further comprises a measurementsystem configured to measure a distance related to the thickness of thebrake pad when the pressure is applied to the sensorized brake pad. Insome embodiments, the measurement system comprises a laser distancesensor. In some embodiments, the controller further comprises: adistance signal receiving portion configured to receive distance signalsfrom the measurement system; and a compressibility data generatorconfigured to generate compressibility data based on the distancesignals received from the measurement system, and to determine whetherthe compressibility data is within predetermined maximum and minimumcompressibility limits.

Some embodiments disclosed herein relate to a method for determiningcalibration data for a sensorized brake pad that comprises pressuresensors configured to output signals in response to pressure applied tothe sensorized brake pad. The method comprises retaining the sensorizedbrake pad in a fixture in a calibration machine; applying, with anactuator of the calibration machine, pressure to the sensorized brakepad; receiving signals outputted from the pressure sensors while thepressure is being applied to the sensorized brake pad; determiningcalibration data for the sensorized brake pad based on the signals;storing the calibration data into a memory; and providing thecalibration data to a user for installing in a controller of a vehicleon which the sensorized brake pad is installed.

In some embodiments, the applying of pressure further comprises applyingthe pressure at a substantially 90 degree angle relative to the frictionelement of the sensorized brake pad. In some embodiments, the applyingof pressure comprises applying a normal force and a shear force to thesensorized brake pad. In some embodiments, the storing of thecalibration data into memory further comprises storing the calibrationdata into memory on-board the sensorized brake pad.

In some embodiments, the method further comprises associating an opticalcode with the calibration data of the sensorized brake pad, andproviding the optical code with the brake pad. In some embodiments, theoptical code comprises a QR code. In some embodiments, the methodfurther comprises receiving a request for the calibration data of thebrake pad in response to scanning of the optical code.

Some embodiments disclosed herein relate to a method of calibrating abraking system on a vehicle. The method comprises identifying a brakepad by referencing a brake pad identifier provided on or with the brakepad; installing the brake pad on the vehicle; receiving calibration datacorresponding to the brake pad identified by the brake pad identifier;and uploading the calibration data to a processing unit of the vehicle.

In some embodiments, the brake pad identifier comprises a code that isunique to each brake pad.

In some embodiments, the brake pad identifier comprises analpha-numeric, a machine-readable, or an electronic code.

In some embodiments, identifying a brake pad further comprises scanningthe code with a code scanner.

In some embodiments, scanning the code with the code scanner generates arequest to receive the calibration data from a database containing thecalibration data.

In some embodiments, receiving calibration data further comprisesreceiving the calibration data via internet communication.

Certain embodiments include a measuring system. The measuring system canbe configured to measure a relative variation of distance. For example,in some embodiments, the measuring system can measure a variation ofdistance between the measuring system and a base plane of the fixture ofthe calibration machine holding the pad during the calibration. Invarious embodiments, the measuring system can enable measurement of thecompression of the friction material when a pressure is applied to thepad. The measurement system can be included in the calibration machineor separate. In various embodiments, the measurement system can enablein-line (e.g., in the manufacturing line) compressibility testing ofeach brake pad.

The devices, systems, and methods described herein have severalinnovative aspects, no single one of which is indispensable or solelyresponsible for their desirable attributes. Neither the Summary above,nor the Detailed Description below, nor the associated drawings, shouldbe interpreted to limit the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are depicted in the accompanying drawings forillustrative purposes, and should in no way be interpreted as limitingthe scope of this disclosure. Various features of different disclosedembodiments can be combined to form additional embodiments, which arepart of this disclosure.

FIG. 1A illustrates a perspective view of a vehicle.

FIG. 1B illustrates a schematic view of a sensorized braking systeminstalled on a vehicle.

FIG. 2A illustrates a perspective view of a sensorized brake pad.

FIG. 2B illustrates a perspective view of the sensorized brake pad inFIG. 2A with the friction material removed to illustrate certaininternal features.

FIG. 3 is a flowchart illustrating steps from the manufacturing of thesensorized brake pad to the calibration of the vehicle with thesensorized brake pad installed.

FIG. 4A illustrates a side view of an embodiment of the calibrationmachine.

FIG. 4B is a close-up view of a portion of FIG. 4A and illustrates anexample of a measuring system.

FIG. 5A illustrates an exploded view of a brake pad, retainer, andconnector that can be used in and/or a part of the calibration machineof FIG. 4A.

FIG. 5B schematically illustrates a side view of the brake pad,retainer, and connector of FIG. 5A in an engaged state.

FIG. 5C illustrates a perspective view of an engagement systemcomprising the connector of FIG. 5A.

FIG. 6 is a flowchart illustrating a calibration data determiningprocess.

FIG. 7 illustrates a side view of another embodiment of a calibrationmachine.

FIG. 8 illustrates a front cross-sectional view of another calibrationmachine with an actuator angle adjustment mechanism.

FIG. 9 illustrates a side view of the calibration machine of FIG. 8.

FIG. 10 illustrates a close-up front cross-sectional view along a line10-10 in FIG. 9 of the actuator angle adjustment mechanism of thecalibration machine of FIG. 8.

FIG. 11 illustrates a close-up side cross-sectional view of the actuatorangle adjustment mechanism of the calibration machine of FIG. 8.

FIG. 12 illustrates a close-up front cross-sectional view of thecalibration machine of FIG. 8.

FIG. 13 illustrates a cage enclosing the calibration machine of FIG. 8.

FIG. 14 illustrates a side view of an embodiment of a torque-basedcalibration machine.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar reference numbers typically identify similar components, unlesscontext dictates otherwise. The illustrative embodiments described inthe detailed description and drawings are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here. The aspects of the present disclosure, as generallydescribed herein, and illustrated in the figures, may be arranged,substituted, combined, and designed in a wide variety of differentconfigurations, all of which are explicitly contemplated and made a partof this disclosure.

Overview

FIG. 1A illustrates a vehicle V, such as a heavy truck. The vehicle caninclude a sensorized braking system 10, such as in one or more of thewheels. The sensorized braking system 10 can aid in braking the vehicle.

FIG. 1B schematically illustrates the sensorized braking system 10. Asshown, the system 10 includes a caliper 12 and disk-shaped rotor 14rotating about an axis of the wheel of the vehicle. A pair of sensorizedbrake pads 20 is installed within a brake caliper 12 that is installedon the vehicle. The brake caliper 12 is installed over a brake rotor 14of the vehicle such that the sensorized brake pads 20 are positioned onopposing sides of the brake rotor 14. The caliper 12 includes pistons 16that engage the respective brake pads 20. In response to a brake command(such as when the driver of the vehicle applies the brakes), the pistons16 press each brake pad 20 against the brake rotor 14. Morespecifically, the brake rotor contacting surfaces 36 of the frictionmaterial 24 contact opposing faces of the brake rotor 14 such that thebrake rotor 14 is clamped by the brake pads 20. Friction between therotor 14 and the brake pads 20 slow the rotation of the brake rotor 14.

FIGS. 2A and 2B illustrate an embodiment of the sensorized brake pad 20.As shown, the sensorized brake pad 20 comprises a backing plate 22, afriction material 24, and one or more pressure sensors 26. In someembodiments, the sensorized brake pad 20 includes an identifier 25, suchas an optical code. The friction material 24 can be formed on thebacking plate 22 and the pressure sensors 26 are embedded within thefriction material 24.

The pressure sensors 26 can be configured to sense the braking force andpressure (e.g., in terms of normal and/or shear forces) applied to thefriction material 24. For example, the pressure sensors 26 can detectthe force applied by the brake rotor 14 when the brake pad 20 is pressedagainst the brake rotor 14 during a brake application. The pressuresensors 26 generate electrical signals. The signals can be transmittedvia cables 15 to a processing unit 18 installed on the vehicle (See FIG.1B). In some configurations, the processing unit 18 may be and/or beintegrated into the vehicle electronic control unit (ECU) or a brakecontrol unit. The processing unit 18 can be configured to receive andprocess the electrical signals from the pressure sensors 26 of the brakepad 20. In some embodiments, the processing unit 18 is configured todetermine the amount of normal and/or shear forces being applied to thefriction material 24 of the brake pad 20.

In some embodiments, by determining the amount of normal and/or shearforces acting on the brake pad 20, the processing unit 18 is capable ofmonitoring the vehicle braking system. For example, the sensorizedbraking system 10 can allow for the detecting of conditions thatindicate both normal and abnormal operation of the braking system. Somevariants of the sensorized braking system 10 may detect the occurrenceof abnormalities such as increased wear, noise and/or vibration. Someembodiments of the sensorized braking system 10 can detect whether thebrake pads 20 are contacting the brake rotor 14 and the amount ofpressure being applied to the brake rotor 14. Certain implementations ofthe sensorized braking system 10 may detect uneven braking between left-and right-side calipers, dragging of the brake pad 20, vibration of thebrake pad 20 within the caliper 12, and/or other abnormalities.

During the manufacturing of sensorized brake pads 20, variances in theconstruction of the pressure sensors and/or the brake pads may causeslight variance in the signal outputs of generally identicallyconstructed pressure sensors 26. The signal output between substantiallyidentically constructed pressure sensors 26 may vary, such as due tomanufacturing variance. For further illustration of the effect ofmanufacturing variance, Table 1 is provided below.

TABLE 1 Sam- Sam- Sam- Applied ple 1 - ple 2 - ple 3 - Sample 1 - Sample2 - Sample 3 - Pressure Normal Normal Normal Shear Shear Shear (bars)(mV) (mV) (mV) (mV) (mV) (mV) 5 14 15 17 4 5 7 53.3 22 25 30 8 10 12101.6 50 55 55 22 25 30 150 75 80 85 35 40 45

Table 1 shows the pressure sensor outputs for three substantiallyidentically manufactured sample brake pads (Sample 1, Sample 2, Sample3) at applied pressures of 5, 53.3, 101.6 and 150 bars. As shown, thevoltage outputs for normal and shear forces vary between the threepressure sensors for a given applied pressure. As a result, depending onthe amount of variance, the processing unit 18 of the vehicle may notaccurately detect the actual pressures on the brake pad 20 wheninstalled on the vehicle. Thus, it can be desirable to provide acalibration system to identify and/or compensate for variability in thebrake pad 20.

Using a Sensorized Brake Pad

FIG. 3 illustrates a process 50 of using (e.g., obtaining, providing,installing, etc.) the sensorized brake pad 20. In some embodiments, theprocess 50 includes certain actions between the manufacture of thesensorized brake pad 20 and a vehicle with the sensorized brake pad 20installed being configured to use the sensorized brake pad 20.

As shown in block 52, in some embodiments, the sensorized brake pad 20is manufactured. For example, the sensorized brake pad 20 is produced onan automated assembly line. Further details related to the manufactureand other aspects of the sensorized brake pad 20 are described in U.S.Pat. No. 9,415,757, which is incorporated herein by reference in itsentirety.

In some embodiments, the process 50 includes the use of a calibrationmachine. The calibration machine can be configured to perform acalibration data determining process. For example, in block 54, thecalibration machine performs a calibration data determining process oneach sensorized brake pad to determine calibration data for eachsensorized brake pad. In some embodiments, the calibration datacomprises a plurality of points (e.g., pressures and associated voltagereadings). In some variants, the calibration data comprises amathematical function, such as a formula for a line or curve thatincludes the plurality of points. The mathematical function can be usedoperatively as specific values for coefficients belonging to thosemathematical formula obtained through a best-fit procedure. In someembodiments, the calibration data is used to determine a polynomial,such as a line. Certain implementations determine the polynomial with alinear, quadratic, cubic or other type of regression analysis. In someembodiments, the calibration data comprises the polynomial and/or thecoefficients of the polynomial. For example, in some variants, thecalibration data comprises the slope and/or y-intercept of a line. Thecalibration data determining process may be performed shortly orimmediately following the final step of manufacturing of the brake pad20. In certain implementations, the calibration data can aid inaccommodating manufacturing variance and/or varying outputs of thepressure sensors. In some embodiments, the calibration machine can beconfigured to determine calibration data specific to each sensorizedbrake pad such that the pressure sensing characteristics of the brakepad is defined by and/or associated with the calibration data. Thecalibration machine and calibration data determining process will bedescribed in further detail below.

In block 56, the calibration data (e.g., the calibration coefficientsobtained during the pad calibration) for each sensorized brake pad 20 isstored. For example, the data can be stored in a database. In block 58,the calibration data (e.g., the coefficients) for a particularsensorized brake pad 20 can be associated with that sensorized brake pad20. For example, the particular calibration data for a given sensorizedbrake pad 20 can be associated with a unique identifier for thatsensorized brake pad 20. In various embodiments, the unique identifierof a particular sensorized brake pad 20 can be used to link (e.g., map)that particular sensorized brake pad 20 with its calibration data and/ordata location. Examples are shown below in Tables 2 (calibration datacomprises voltages at various pressures and/or torques) and 3(calibration data comprises the calibration coefficient):

TABLE 2 Identifier Calibration Data Pressure (Bar) SP (V) ABC123 5.721.69E−02 10.89 3.41E−02 16.08 4.80E−02 21.18 6.31E−02 31.25 9.59E−0221.19 6.31E−02 41.20 1.28E−01 51.00 1.62E−01 60.93 1.94E−01 Torque(daNm) SP (V) DEF456 25.47 8.54E−03 42.61303711 1.81E−02 62.318634033.05E−02 81.36339722 4.37E−02 118.24 7.31E−02 84.63253174 4.62E−02157.2422607 1.05E−01 198.3201477 1.45E−01 238.9833069 1.85E−01Pressure_Dyno (Bar) SP (V) GHI789 5.63 2.02E−02 10.82 3.99E−02 16.045.42E−02 21.16 6.91E−02 31.22 1.03E−01 21.18 6.86E−02 41.20 1.35E−0151.06 1.70E−01 60.91 2.04E−01

TABLE 3 Identifier Calibration Data ABC123 Linear Coefficient: 318.96DEF456 Linear Coefficient = 809.43, Power coefficient = 0.7312 GHI789Linear Coefficient: 300.86

In block 60, the sensorized brake pad 20 is installed on a vehicle, suchas by being assembled into the braking unit 10. In certainimplementations, the sensorized brake pad 20 that is installed on thevehicle is identified and the calibration data for that sensorized brakepad 20 is identified and/or provided. In certain embodiments, thecalibration data stored in the database is cross-referenced and/orlinked to the sensorized brake pad 20 that is installed on the vehiclesuch that the calibration data specific to the sensorized brake pad 20may be installed to the processing unit 18 of the vehicle.

In block 62, the processing unit 18 of the vehicle on which thesensorized brake pads 20 are installed is provided (e.g., uploaded) withthe calibration data. For example, in some configurations, thecalibration data may be requested in response once identified andcross-referenced in block 60. In some embodiments, the request may causethe calibration data to be downloaded and/or received by the processingunit 18 via the internet. The data may be requested, provided and/ordownloaded to the processing unit 18 via a wired or wirelesscommunication system. For example, the installer may connect theprocessing unit 18 to a computer, diagnostic tool or memory storagedevice which uploads the calibration data to the processing unit 18. Insome embodiments, the processing unit 18 may download the calibrationdata without an installer and wirelessly via over-the-air softwareupdates. In certain configurations, the calibration data stored in theon-board memory of the brake pad 20 is uploaded to the processing unit18. The processing unit 18 can receive the calibration data and thebraking system of the vehicle can be calibrated with the sensorizedbrake pads 20 that are installed on the vehicle. In various embodiments,the processing unit 18 may use the calibration data to facilitateaccurate interpreting of the output signals from the pressure sensorsand/or determining the amount of pressure applied on the brake pads 20.

Associating a Particular Brake Pad with its Calibration Data

As mentioned above, calibration data (e.g., coefficients) can beassociated with the sensorized brake pad 20. In some embodiments, thesensorized brake pad 20 may be identified by an identifier provided onand/or with the brake pad 20. In some variants, the identifier can beused to link the sensorized brake pad 20 with its associated calibrationdata. In some embodiments, the identifier may be used to search thedatabase for the corresponding calibration data specific to thesensorized brake pad 20 installed on the vehicle. The identifier may beused to request the calibration data of the brake pad 20 and theprocessing unit 18 may be provided with the corresponding calibrationdata (e.g., as shown in block 62 of FIG. 3). In some embodiments, theidentifier may be provided with the sensorized brake pad 20, such as ona box containing the sensorized brake pad 20 or documentation providedwith the sensorized brake pad 20.

In some implementations, the identifier may be an alpha-numeric codethat is provided (e.g., engraved, stamped, printed, labeled, etc.) onthe sensorized brake pad 20, such as on the backing plate 22. Eachsensorized brake pad 20 may have a unique identifier. In someembodiments, the code may be provided to a computer or diagnostic toolwhich requests, retrieves and uploads the calibration data to thevehicle. In certain embodiments, the vehicle may prompt the installerfor the code such that the vehicle may retrieve the calibration data forthe brake pad 20. In other embodiments, the processing unit 18 may beprovided with the identifier such that the processing unit 18automatically retrieves the calibration data via over-the-aircommunication. In some variants, the identifier may be amachine-readable code. For example, the identifier can include anoptical code, such as a bar code, Quick Response (QR) code, etc. Theidentifier can be provided on and/or with the sensorized brake pad 20.The identifier may be scanned (e.g., via a scanner, reader and/orcamera) to identify the sensorized brake pad 20. In some embodiments,the code may be used to access and/or search the database to identifyand/or provide the calibration data specific to the sensorized brake pad20. In some embodiments, a request for the calibration data of the brakepad 20 may be generated in response to scanning of the identifier.

In some embodiments, the identifier may be an electronic tag such as anRFID chip that is provided on and/or with the sensorized brake pad 20.The electronic tag may be sensed by a tag reader vehicle such that thesensorized brake pad 20 installed on the vehicle is identified and thecorresponding calibration data is provided to the vehicle. In someembodiments, the vehicle may be equipped with a tag reader such that thevehicle may automatically identify and obtain the calibration dataspecific to the sensorized brake pad 20.

In certain embodiments, the identifier may be comprised of electronicdata stored in on-board memory of the brake pad 20. The electronic datamay be read by the processing unit 18 such that the sensorized brake pad20 installed on the vehicle is identified and the correspondingcalibration data is obtained by the vehicle. In some embodiments, thecalibration data may be stored in the on-board memory of the brake pad20 such that the processing unit 18 receives, recognizes and calibratesthe braking system according to the calibration data stored in on-boardmemory of the brake pad 20.

Example Calibration Machine

FIG. 4A shows the mechanical structure of the calibration machine 100.The calibration machine 100 comprises a fixture or base 110, a brake padretainer 120, an actuator 130, a pressure plate 140, a support column150 and a controller 160. As will be described in further detail below,during the calibration data determining process 200, the calibrationmachine 100 applies a load to the sensorized brake pad 20 in a mannerthat simulates (e.g., is substantially identical) to the loading thatthe brake pad 20 experiences when installed on the vehicle and thebrakes are applied. Applying pressure to the brake pad 20 in such amanner helps ensure that the outputs of the pressure sensors can beaccurately associated with the loading when installed on the vehicle. Inthe illustrated configuration, the calibration machine 100 is configuredto apply pressures of about 5 bars to about 150 bars to the brake pad20.

Base Fixture

The base 110 is comprised of a rigid fixture that provides stability andsupport when operating the calibration machine 100. During thecalibration data determining process 200, the braking pad 20 will becompressed at sustained pressures, such as between 5 bars to 150 barswhile pressure and distance measurements are recorded. Therefore, it ispreferable that the base 110 has a mass, shape, geometry, construction,etc. to provide the calibration machine 100 with mechanical strength anda rigid foundation to avoid displacement, deformation and/or instabilitywhen pressure is applied to the brake pads 20 during the calibrationdata determining process 200. Preferably, the base 110 is formed from ametal, such as cast iron, stainless steel, etc.

Brake Pad Retainer

FIG. 5 illustrates the brake pad retainer 120. The brake pad retainer120 retains and secures the braking pad 20 in a fixed position duringoperation of the calibration machine 100. The brake pad retainer 120 canbe configured to hold the braking pad 20 fixed when normal and shearforces are applied to the friction material 24 of the braking pad 20.The brake pad retainer 120 may have a cavity 122 that is recessed from asurface of the brake pad retainer 120. The braking pad 20 is insertedinto and received by the cavity 122. In some embodiments, the cavity 122has a shape, depth and/or geometry that generally corresponds to theshape, thickness and/or geometry of the backing plate 22 of the brakepad 20. The cavity 122 can have a configuration such that the backingplate 22 may fit snugly in the cavity 122 and/or such that the brake pad20 is generally fixed relative to the cavity 122 when shear forces areapplied to the brake pad 20. The brake pad 20 can be retained within thebrake pad retainer 120 such that the brake pad 20 does not slip (e.g.,move more than 5 mm) when shear forces are applied to the brake pad 20.Slipping or movement of the brake pad 20 relative to the brake padretainer 120 may cause inaccuracies in the calibration data determiningprocess 200 due to incomplete transmission or transfer of the pressuresto the brake pad 20. In some embodiments, a smaller amount of pressuremay be transferred to the brake pad 20 causing inaccurate determinationof calibration data. Inhibiting or preventing slippage can be a safetyfeature, such as to reduce the chance of a brake pad under load slidingout of the calibration machine 100 at a high rate of speed.

In some configurations, the cavity 122 may have a depth of between 3-5mm, which may be similar or equal to the thickness of the backing plate22. Preferably, the cavity 122 has a depth of at least 3-4 mm. In someconfigurations, the shape, depth and/or geometry of the cavity 122 mayvary such that the brake pad 20 may be quickly removed and inserted intothe brake pad retainer 120 while being sufficiently stable duringcalibration operations. For example, the leading edges (e.g., uppercorners) of the cavity 122 may be chamfered or filleted.

In some configurations, brake pad retaining elements (not shown) may beformed within the cavity 122 or on a surface of the brake pad retainer120 which may mechanically hold and/or inhibit slippage of the brake pad20 within the cavity 122 during the calibration data determining process200. For example, the bottom or sidewalls of the cavity 122 may havefeatures that protrude and/or recess into the cavity 122. The brake padretaining elements may engage corresponding features in the backingplate 22 of the brake pad 20 (e.g., tabs, holes, slots, notches,cut-outs, grooves, etc.) such that the brake pad 20 is secured to thebrake pad retainer 120. In some variants, the brake pad 20 is secured inthe brake pad retainer 120 in a manner that is substantially similar tothe manner in which the brake pad 20 is secured to the brake caliper 12in the vehicle. For example, the brake pad retaining elements on thebrake pad retainer 120 may be substantially similar to the brake padretainer 120 with which the brake pad 20 is secured to the brake caliper12 in the vehicle. In some configurations, the brake pad retainer 120may be configured without a cavity 122 such that the brake pad retainingelements are positioned on a surface of the brake pad retainer 120. Incertain configurations, the brake pad retaining elements secure thebrake pad 20 to the brake pad retainer 120 and prevent the brake pad 20from slipping during the calibration data determining process 200. Insome configurations, the brake pad retainer 120 may comprise anystructure for holding or locking the brake pad 20 fixed during theapplication of pressure during the calibration data determining process200.

The brake pad retainer 120 may have a mass, shape, geometry,construction, etc. in order to provide mechanical strength and a rigidfoundation to avoid any displacement, deformation or instability of thebrake pad retainer 120 when pressure is applied to the brake pads 20.Preferably, the brake pad retainer 120 is formed from a stainless steelplate. In some configurations, the brake pad retainer 120 may havehandles 124 positioned on the brake pad retainer 120 to allow a user toconveniently grab and hold the brake pad retainer 120, for example,during removal and installation of the brake pad retainer 120.

The brake pad retainer 120 may be fixed to the base 110 by fasteners(not shown) or other fastening arrangements. The fasteners may includenuts and bolts that are configured to allow the brake pad retainer 120to be removably fastened to the base 110 while securely fastening thebrake pad retainer 120 to the base 110. The fasteners can be configuredto withstand the pressures applied to the brake pad retainer 120 withoutdeforming or failing, such as for at least one million duty cycles. Insome configurations, the fasteners may have a quick-release arrangementsuch that the brake pad retainer 120 may be quickly removed andreplaced, for example, when transitioning a production line betweendifferent models or types of brake pads. For example, the calibrationmachine 100 may utilize different brake pad retainers 120 for differentmodels or types of brake pads 20. Accordingly, the quick releasefastener system may allow quick replacement of the brake pad retainer120 between calibration runs of different types of brake pads 20 and/orwhen a brake pad retainer 120 is worn.

As illustrated in FIGS. 5A and 5B, the machine 100 can be configured toengage with the brake pad 20. In some embodiments, the brake padretainer 120 has a connector hole 126. A connector 170 of thecalibration machine 100 can extend through the hole 126 to connect tothe connector 28 of the brake pad 20, as illustrated in FIG. 5B.Connecting the connectors 28, 170 electrically connects the pressuresensors 26 of the brake pad 20 to the calibration machine 100. This canenable the electrical signals from the pressure sensors 26 to bereceived, recognized and/or read by the controller 160 of thecalibration machine 100. The connectors 28, 170 may have a male-femalearrangement with a corresponding shape and configuration. The connector170 of the calibration machine 100 may have a shape and configurationthat corresponds to the connector on a vehicle that connects to theconnector 28 of the brake pad 20. The connectors 28, 170 may have acorresponding pin and electrode layout. The controller 160 of thecalibration machine 100 may receive similar information (e.g.,electrical signals) from the brake pad 20 that the processing unit 18 ofthe vehicle would receive when connected to the brake pad 20.

Some embodiments include a system that is configured to engage theconnector 170 with the brake pad 20. For example, as shown in FIG. 5C,the system can be configured to extend and retract (e.g., raise andlower) the connector 170 into and out of engagement with the brake pad20. As shown, the system can include an actuator 174, such as a motor,that drives a translating shaft 176. The shaft 176 can be coupled withconnecting rods 178 to a plate 180. In some embodiments, when the shaft176 translates in one direction the connector 170 is extended intoengagement with the brake pad 20, and when the shaft 176 translates inthe generally opposite direction the connector 170 is retracted out ofengagement with the brake pad 20. As shown, the system can include oneor more shock absorbers 182. In some embodiments, the shock absorbers182 cushion and/or dampen the engagement of the connector 170 with thebrake pad 20. In some embodiments, the shock absorbers 182 enable theconnector 170 to rotate relative to the brake pad 20. This canfacilitate engaging the connector 170 with the brake pad 20 and/or canreduce the chance of bending the contact (e.g., pins) of the connector170.

In some configurations, the connector 170 may be connected to thecontroller 160 by a cable. In some configurations, the cable may have alength of at least 1-2 meters. In some configurations (e.g., for someconfigurations with five piezoceramic sensors and one temperaturesensor), the connector 170 may comprise a 12-pin connector that iscompatible with the ECU of the vehicle. The cable may provide signaltransmission of at least 12 wires (e.g., equivalent to the number ofpins). In some configurations, the controller 160 may communicatewirelessly with the brake pad 20. In certain configurations, each brakepad 20 is equipped with a wireless transceiver.

In some configurations, the connectors 28, 170 may be connected manuallyby a user, for example, when the user manually inserts the brake pad 20into the cavity 122 by hand. In some configurations, the cavity 122 andconnectors 28, 170 may be configured (e.g., shaped, positioned inalignment, etc.) to automatically connect when the brake pad 20, such aswhen the brake pad 20 is inserted into the cavity 122. In some variants,inserting the brake pad 20 into the cavity 122 causes positiveengagement of the connectors 28, 170. For example, the connector 170 maybe integrally formed in the cavity 122 and aligned with the connector 28such that the connectors 28, 170 are positively engaged when the backingplate 22 is inserted into the cavity 122. In some implementations,removal of the brake pad 20 from the cavity 122 causes disconnection ofthe connectors 28, 170.

In some configurations, the connector 170 may be connected to anactuator (not shown) that extends into the connector hole 126 such thatthe connector 170 of the calibration machine 100 is pushed into positiveengagement with the connector 28 of the brake pad 20 through theconnector hole 126. The actuator may retract such that the connector 170of the calibration machine 100 disengages with the connector 28 of thebrake pad 20. In various embodiments, retraction of the connector 170does not cause damage to the connectors 28, 170. The actuator may becontrolled by the controller 160 such that connection of data from thepressure sensors 26 of the brake pad 20 to the calibration machine 100may be fully automated. This can increase production efficiency and/orvolume. The calibration machine 100 can be configured to quickly andsafely connect to the connector 28 on the brake pad 20 once it ispositioned within the cavity 122 at the beginning of the calibrationdata determining process 200.

The connector 170 can be configured to accommodate and/or engage withdifferent types (e.g., sizes and configurations) of the brake pad 20.Different types of the pad 20 can be required due to, for example, thesize and characteristics of the vehicle on the pad is to be used. Forexample, an instance of the pad 20 for use on a compact passenger carmay be a different type than an instance of the brake pad 20 for use ona heavy truck. In some implementations, the connector 170 can movewithin the machine 100. For example, the connector 170 can be configuredto move in x, y, and/or z directions relative to the base 110. This canpermit the connector 170 to accommodate and/or engage with various typesof the brake pad 20, and thus can enable the machine 100 to be used witha wide variety of the brake pad 20. This can reduce or avoid the need tomake time-consuming changes to the manufacturing line due to a change inthe type of brake pad 20 being produced. In some embodiments, themovement of the connector 170 is automated, such as by the controllerinstructing one or more motors to move the connector 170 to a certainposition based on the type of brake pad 20.

In some embodiments, the connector 170 can change its orientation. Forexample, in some implementations, the connector 170 can rotate relativeto the base 110, such as about a generally vertical axis of rotation. Insome variants, the connector 170 can rotate by at least about: 45°, 90°,135°, 180°, or otherwise. In some implementations, the machine 100 isconfigured to change the connector 170 from a generally verticalorientation to a generally horizontal orientation.

In some variants, the connector 170 is adapted to reduce the chance ofdamage during engagement with the pad 20. For example, the connector 170can include damped pins that engage with the pad 20. In case of wrongpositioning of the pad into the calibration machine, such damped pinscan reduce or avoid mechanical damage or disruption during thecalibration process.

Actuator(s)

With reference to FIG. 4A again, the illustrated calibration machine 100includes a linear actuator 130. The actuator 130 can be controlled bythe controller 160. Similar to the discussion above regarding theconnector 170, the actuator 130 can be configured to adjust toaccommodate a wide variety of configurations of the brake pad 20. Forexample, the actuator 130 can be configured to move in x, y, and/or zdirections relative to the base 110.

The actuator 130 can apply pressure to the brake pad 20. In certainembodiments, the actuator 130 is supported at an angle relative to thebrake pad 20. This can enable the actuator 130 to apply normal and shearforces to the friction material 24 of the brake pad 20. The normal andshear forces applied by the actuator 130 can simulate (e.g., besubstantially identical to) the pressures experienced by the brake pad20 during a braking application on a vehicle. The shear or tangentialpressure applied to the friction material 24 of the brake pad 20 isanalogous and/or equivalent to the braking torque applied to thefriction material 24 of the brake pad 20 by the brake rotor of thevehicle. The normal pressure applied by the actuator 130 is analogousand/or equivalent to the force applied by the brake caliper 12.

The actuator 130 may include a cylinder 132 and a rod 134. The rod 134moves relative to the cylinder 132 such that the actuator 130 extendsand retracts in substantially a straight line. In the configurationshown in FIG. 4A, the actuator 130 is supported at a first end by thesupport pillar 150 which is attached to the base 110. In someembodiments, the actuator 130 is held fixed by a pinned connection withthe support pillar 150. The actuator 130 is attached to a pressure plate140 at a second end. The actuator 130 may be attached to the pressureplate 140 by a pivoting hub 142 and a load pin 144. The pressure plate140 contacts the friction material 24 of the brake pad 20 such that thepressure plate 140 applies a pressure to the friction material 24 whenthe actuator 130 extends. The load pin 144 allows the pressure plate 140to rotate relative to the actuator 130 such that the pressure plate 140contacts the surface 36 of the friction material 24 such that thepressures are substantially evenly distributed across the surface 36 ofthe friction material 24. Preferably, the pressure plate 140 isconfigured (e.g., sized) to contact substantially the entire surface 36of the friction material 24.

In some implementations, the actuator 130 is connected to an energizingunit, such as a compressor 136 that is controlled by the controller 160.The compressor 136 may compress hydraulic fluid or pneumatic gas toincrease pressure within the cylinder 132 such that the rod 134 extendsand applies pressure to the brake pad 20. The compressor 136 is capableof quickly and accurately providing the actuator 130 with sustainedpressures of at least 5 bars to 150 bars for at least several seconds.Preferably, the actuator 130 provides pressure at an accuracy of atleast 5% for lower pressures (e.g., less than 25 bars) and 2-3% forhigher pressures (e.g., greater than 25 bars) in order to have similaraccuracy in the calibration data of the brake pad 20. Other types ofenergizing units are contemplated. For example, certain embodimentsinclude an electromechanical actuator such as an endless screw rotatedby an electric motor. Some embodiments include non-linear actuators.Pressure may be applied to the friction material 24 of the brake pad 20by a variety of mechanical and/or electromechanical mechanisms.

In some configurations, the actuator 130 has a stroke of sufficientlength such that the pressure plate 140 may be moved a distance farenough away from the brake pad 20 to provide clearance such that thebrake pad 20 may be easily installed and removed within the brake padretainer 120. In some configurations, the actuator 130 and/or thecompressor 136 may be equipped with a relief valve such that thehydraulic pressure of oil (or gas) within the actuator 130 may bequickly removed, released and/or bled. Release of the hydraulic pressurecauses the rod 134 to quickly retract within the cylinder 132 such thatthe pressure plate 140 is quickly moved away from the brake pad 20. Inyet another configuration, the support pillar 150 may include a tiltingor rotating mechanism to move or rotate the actuator 130 away from thebrake pad 20 such that the brake pad retainer 120 may be quickly andeasily removed and inserted. In some configurations, the calibrationmachine 100 may provide alternative means for providing clearancebetween the brake pad retainer 120 and the pressure plate 140 such thatthe brake pad 20 may be removed from the brake pad retainer 120.

During the calibration data determining process 200, the brake pad 20may be calibrated at several measuring points of varying magnitudes ofapplied pressure. For example, in some configurations, the outputs ofthe pressure sensors 26 may be measured at four measuring points ofapplied pressures of 5, 53.3, 101.6, 150 bars. The magnitude of eachapplied pressure P_(i) is determined according to the following equation(e.g., assuming a range of pressures between 5 and 150 bars):

$P_{i} = {5 + {\left( {i - 1} \right)*\frac{145}{N - 1}}}$

Where:

P_(i)=the magnitude of each applied pressure;

i=an index of the specific measuring point; and

N=the total number of measuring points to be taken during thecalibration.

Preferably, the brake pad 20 is calibrated at a minimum of 4 points anda maximum of 10 points. It should be understood to one of ordinary skillin the art that the calibration machine 100 is not limited to appliedpressures of 1-150 bars and 4-10 measuring points. In someconfigurations, the applied pressure may be applied and varied accordingto predetermined pressure-time curves.

In some configurations, the actuator 130 applies the normal and shearforces to the friction element 14 of the brake pad for a duration of1-10 seconds. The applied pressure at each measuring point can be heldgenerally constant for a duration of about 1-10 seconds. In somevariants, the brake pad 20 may be held under constant pressure while themagnitude of the applied pressure changes. For example, the appliedpressure may increase between sustained applied pressures of 5, 53.3,101.6, 150 bars. The increasing or decreasing of the applied pressuremay be varied to test the pressure sensor's dynamic response.

In some embodiments, the machine 100 is configured to conductcompressibility testing on the brake pad 20. Compressibility testing canaid in detecting defects in the brake pad 20, such as defects that mayhave been created during the manufacturing process (e.g., during theheat-treatment and/or curing process). In various embodiments, themachine 100 can be configured to conduct compressibility testing on eachbrake pad 20 tested. This can provide for 100% inspection of the brakepads 20 being produced, which can be an improvement over quality controlmethods that involve testing only samples and using statisticalpredictions.

In some embodiments, the machine 100 tests compressibility using ameasurement system that is configured to monitor a distance, such as thethickness of the pad 20. In some implementations, the measurement systemincludes a proximity sensor 148, such as a laser distance sensor, thatis configured to measure the distance. For example, as shown in FIG. 4B,the proximity sensor 148 can be positioned on the pressure plate 140 andcan measure a distance D between the pressure plate 140 and the backingplate 22, retainer 120, or base 110. In some embodiments, the distanceis monitored during at least a portion of the calibration process. Forexample, as the distance can be monitored as the actuator 130 appliesload (e.g., varying amounts of load) to the brake pad 20. The resultingdistance data can be provided to the controller and/or can be used todetermine deflection of the brake pad 20. The deflection of the brakepad 20 can be compared with certain values, such as minimum and maximumacceptable amounts, to determine whether the brake pad 20 is withinacceptable quality control limits.

Support Pillar

In the configuration shown in FIG. 4A, the actuator 130 is attached tothe base 110 by a support pillar 150. The support pillar 150 can beattached to the base 110 at one end and the actuator 130 at an oppositeend. The support pillar 150 holds and supports the actuator 140 inalignment over the base 110 and the brake pad retainer 120. The supportpillar 150 may house hydraulic lines, pneumatic lines and/or wires thatconnect the actuator 130, the compressor 136 and the controller 160 toeach other.

The actuator 130 may be connected to the support pillar 150 by an angleadjustment mechanism (not shown). The angle adjustment mechanism can beconfigured to adjust an angle θ between the actuator 130 and a planeformed by a brake rotor contacting surface 36 of the friction material24 upon which the pressure is applied. In some embodiments, as shown inFIG. 4A, the actuator 130 and the surface 36 of the friction material 24form the angle θ. The angle θ can be determined according to arelationship between the pressure and frictional pressures to besimulated (e.g., to mimic those experienced by the brake pad 20 whenmounted in the vehicle). In some embodiments, the ratio between normalforces (e.g., corresponding to the compressive pressure applied by thecalipers) and the shear forces (e.g., corresponding to the frictionpressures from engagement with the rotor) is substantially similar tothe dynamic friction coefficient μ of the brake pad 20. The coefficientof friction can be thought of as the ratio between the force necessaryto move one surface horizontally over another and the pressure betweenthe two surfaces. Generally, the value of the dynamic frictioncoefficient μ is a known coefficient based on, for example, the designof the brake pad 20 and the chosen friction material 24. Accordingly,the angle θ of the actuator 130 may be determined using the followingequation:

$\mu = {\frac{F_{t}}{F_{N}} = {\tan\mspace{14mu}\theta}}$

Where:

μ=the dynamic friction coefficient;

F_(t)=the shear or tangential force;

F_(N)=the normal force; and

θ=the angle between the actuator 130 and a plane formed by a surface 36of the friction material 24 upon which the force is applied.

Pressure can be determined by multiplying the force by the area of thefriction material 24 that is in contact with the pressure plate 140.Applying the shear and normal forces at the angle θ enables thecalibration machine to apply substantially identical pressures duringthe calibration data determining process 200 as experienced by the brakepad 20 during actual braking applications. For example, the angle θ canbe adjusted so that the ratio of the shear force (e.g., the generallyhorizontal component of force) and the normal force (e.g., the generallyvertical component of force) applied to the brake pad 20 isapproximately equal to the coefficient of friction. Failing to achieve acondition similar to the friction coefficient in terms of the abovepressure ratio may generate erroneous calibration data for the brake pad20 because the brake pad 20 may experience different pressures thanthose during actual braking applications of the vehicle. Certainimplementations include measuring a static friction coefficient, whichis used as a reasonably close approximation for the dynamic frictioncoefficient. In some implementations, the static friction coefficient isgreater than the dynamic friction coefficient by less than or equal toabout 10%.

The angle adjustment mechanism allows the angle θ to be adjusted. Someembodiments are configured to adjust within typically a range of 50-80degrees relative to plane formed by the surface 36 of the frictionmaterial 24. In some variants, the angle θ is at least about 68.2degrees. The angle adjustment mechanism may include a mechanical angleadjustment structure for varying and fixing the angle θ between theactuator 130 and the surface 36 of the friction material 24. Forexample, the angle adjustment structure may include a mechanical featurefor raising or lowering the support column 150 relative to the base 110such that the angle θ increases or decreases. In some variants, thesupport column 150 may move laterally relative to the base 110 to adjustthe angle θ. In some configurations, the angle adjustment mechanism mayallow the actuator 130 to be angled relative to the surface 36 of thefriction material 24 such that the actuator 130 is non-orthogonal to thesurface 36 of the friction material 24. For example, the angleadjustment mechanism may include features that enable moving of thesupport column 150 laterally (e.g., left or right relative to FIG. 4A)and transverse (into or out of the page relative to FIG. 4A). In someconfigurations, the support column 150 may tilt such that the angle θbetween the actuator 130 and the support column 150 may be adjusted. Asmentioned above, the angle θ can facilitate simulating a coefficient offriction. For example, the angle θ can be adjusted such that the ratioof the generally horizontal component of the force applied by theactuator 130 and the generally vertical component of the force appliedby the actuator 130 is approximately equal to the coefficient offriction. In some embodiments, the coefficient of friction is betweenabout 0.3 and about 0.6. Preferably, the coefficient of friction isbetween about 0.4 and about 0.5, such as 0.42 or 0.43.

In some configurations, the base 110 may have a mounting system. Themounting system can include flanges, pillars and/or guides to mount thesupport pillar 150 to the base 110. In some configurations, the base 110may include adjustment mechanisms to allow the position and/or angle ofthe support pillar 150 to be adjusted such that the angle of the piston140 relative to the base 110 and brake pad retainer 120 may be adjusted.For example, the base 110 may have guides that allow adjustment of thesupport pillar 150. The support pillar 150 may be fastened to the guidesby blocking nuts which lock the angle and/or position of the supportpillar 150 relative to the base 110. The mechanical components, such asthe guides and blocking nuts, can provide strength for structuralstability and durability. This can be achieved, for example, bystructural dimensioning the components and/or by choosing high dutystainless steel materials with a high degree of mechanical resistance.

It should be understood to one of ordinary skill in the art that thecalibration machine 100 is not limited to the angle adjustmentmechanisms described and may incorporate any means for adjusting andmaintaining the angle between the actuator 130 and the surface 36 of thefriction material 24. For example, in some configurations, the angle θmay be adjusted by varying the position of the brake pad 20 relative tothe actuator 130.

Load Cells

In some configurations, the calibration machine 100 has pressure sensingfeatures adapted to sense an absolute pressure, such as load cells,shear sensors, or pressure measuring devices. The load cells can beconfigured to measure the normal and/or shear forces applied by theactuator 130 to the brake pad 20 during the calibration data determiningprocess 200. The load cells allow the normal and shear forces to bemonitored to ensure that the calibration machine 100 is operatingnormally. In some embodiments, the load cells sense the angle θ and/orare used to determine the angle θ between the actuator 130 and thesupport column 150. This can aid in ensuring that the actuator 130 ispositioned at the correct angle.

In certain configurations, a load cell may be installed between the endof the rod 134 of the actuator 130 and the pressure plate 140. Forexample, the load pin 144 may comprise a pressure sensor or strain gaugethat is used to measure pressures along the X- and Y-axes. In certainimplementations, the load pin 144 allows the normal and shear forcesapplied to the brake pad 20 to be measured while also allowing rotationof the pressure plate 140 relative to the actuator 130. In somevariants, the load pin 144 may sense and measure the angle θ formedbetween the actuator 130 and the pressure plate 140.

In certain configurations, a load cell or a plurality of load cells maybe positioned between the base 110 and the brake pad retainer 120,between the actuator 130 and the support column 150, integrated withinthe brake pad retainer 120 and/or integrated within the actuator 130. Itshould be understood to one of ordinary skill in the art that the loadcells are not limited by position, type or quantity such that thecalibration machine 100 may accurately measure pressures applied to thebraking pad 20 by the actuator 130 before, during, and after thecalibration data determining process 200.

Controller

The controller 160 can be configured to control operation of thecalibration machine 100. In some embodiments, the controller 160 isconnected to the actuator 130 and/or the compressor 136 to control thecalibration data determining process 200. The controller 160 can beconnected to the brake pad 20 and/or to the load cells such that thepressures exerted by the actuator 130 may be monitored. Someconfigurations include a user interface through which the calibrationdata determining process 200 may be monitored and manually controlled bya user. The controller 160 is connected to the pressure sensors 26 ofthe brake pad 20 via cables. However, in some configurations, thecontroller 160 may be wirelessly connected to the pressure sensors 26 ofthe brake pad 20.

The controller 160 comprises a processor and memory that are connectedtogether and configured to perform the calibration data determiningprocess 200. The processor can be any of a wide variety of processors,such as a microprocessor or other processor without limitation. Thememory can be any of a wide variety of storage media, whether or notremovable, and can include one or more arrays of RAM, ROM, EPROM,EEPROM, FLASH, and the like without limitation. The memory has storedtherein a number of routines that are executable on the processor tocause the calibration machine 100 to perform the calibration datadetermining process 200. The controller 160 can be positioned in acontrol panel, which can be located on the calibration machine 100 orremotely.

In some configurations, the controller 160 is connected to a storagedevice in which the calibration data determined for each brake pad 20 bythe calibration machine 100 is stored therein. Access to and retrievalof the calibration data may be provided via the internet, wired and/orwireless communication.

System Operation

An example of the calibration data determining process 200 isillustrated in FIG. 6. At block 202, the process 200 begins by loadingand securing the brake pad 20 into the calibration machine 100. In someembodiments, the backing plate 22 of the brake pad 20 is inserted intothe cavity 122 of the brake pad retainer 120. The brake pad 20 can befixed, secured and/or fastened to the brake pad retainer 120 such thatthe brake pad 20 is inhibited from slipping or moving when the actuator130 applies normal and shear forces to the brake pad 20. The connector28 of the brake pad 20 can be connected to the connector 170 of thecalibration machine 100. In some variants, signal outputs of thepressure sensors 26 are received by the controller 160. The brake pad 20may be loaded into the calibration machine 100 manually by a user orautomatically as part of an automated brake pad loading process. In someconfigurations, the calibration machine 100 may be positioned on anautomated brake pad assembly line such that the brake pads 20 areautomatically loaded into the calibration machine 100. In someimplementations, the process 200 may be performed immediately followingthe final step of manufacturing.

At block 204, the calibration machine 100 applies pressure to the brakepad 20. In the illustrated configuration, the pressure plate 140 and thefriction material 24 of the brake pad 20 are brought into contact. Theactuator 130 can extend and/or press the pressure plate 140 against thefriction material 24 of the brake pad 20. The brake pad 20 can becompressed between the pressure plate 140 and the brake pad retainer120. The pressure can be substantially applied evenly across the surface36 of the friction material 24. While the pressure is being applied bythe actuator 130, the measurements from the load pin 144 may bemonitored and/or compared with other actuator load measuring devices(e.g., hydraulic pressure, actuator pressure sensors, etc.) to verifythat the actuator 130 is applying the correct amount of pressure to thebrake pad 20.

At block 206, while the pressure is being applied to the brake pad 20,the outputted signals from the pressure sensors 26 of the brake pad 20are received and/or recorded by the controller 160. For example, in theillustrated configuration, when the actuator 130 applies a pressure of 5bars, the controller 160 can receive and/or record a signal from apressure sensor 26 that measures a normal force and a signal from apressure sensor 26 that measures shear force. For example, a signalindicative of about 15 mV for normal force and about 5 mV for shearforce may be received. In various embodiments, the outputted signalsfrom the pressure sensors 26 indicate that the normal and shear forcesare received by the controller 160 via the connectors 28, 170.

At block 208, the controller 160 determines calibration data specific tothe brake pad 20 based on the outputted signals from the pressuresensors 26 in response to the normal and shear forces applied to thebrake pad 20. For example, in the illustrated configuration, thecontroller 160 determines calibration data based on the outputtedvoltages of 5 mV (shear) and 15 mV (normal) from the pressure sensors 26at an applied pressure of 5 bars. Accordingly, when the brake pad 20 isinstalled on a vehicle and the processing unit 18 is provided with thecalibration data, the processing unit 18 can determine that 5 bars ofpressure is applied to the brake pad 20 when the pressure sensors 26output voltages of 5 mV (shear) and 15 mV (normal).

At block 210, the calibration data specific to the brake pad 20 isstored into memory. In various embodiments, the calibration data isstored in a database. The calibration data may be uploaded from thedatabase to the processing unit 18 of the vehicle. In someconfigurations, the calibration data may be stored in memory that islocated on-board the brake pad 20. In some configurations, theprocessing unit 18 is provided with the calibration data when the brakepad 20 is installed on the vehicle.

At block 212, it is determined (e.g., by the controller 160) whethercalibration data for additional measuring points (e.g., additionalapplied pressures) remain to be determined during the calibration datadetermining process 200. If calibration data for additional pressureshas yet to be determined, the applied pressure is adjusted at block 214and blocks 204 to 210 are repeated to determine calibration at theadjusted applied pressure. For example, in the illustratedconfiguration, after the calibration data has been obtained (e.g.,determined) at an applied pressure of 5 bars, it is determined thatadditional calibration data is to be obtained at additional appliedpressures (YES at block 212). In some embodiments, calibration data isto be additionally obtained (e.g., determined) at applied pressures of53.3, 101.6 and 150 bars. Accordingly, at block 214, the appliedpressure is adjusted to increase or decrease the normal and shear forcesapplied to the brake pad 20. Then, blocks 204 to 210 are repeated toobtained calibration data for each of the applied pressures of 53.3,101.6 and 150 bars. If no further pressures remain to be tested (NO atblock 212), the calibration data determining process 200 ends. Forexample, in the illustrated configuration, after calibration data hasbeen obtained for applied pressures of 5, 53.3, 101.6 and 150 bars, itis determined at block 212 that no further pressures remain to be testedand thus, the calibration data determining process 200 ends.

In some configurations, if an abnormality or error is suspected oroccurs during the calibration data determining process 200, it may alsobe determined whether blocks 204 to 210 should be repeated. Measuringpoints may be repeated to ensure and/or to validate the propercollection of calibration data.

Testing

Prior to and/or after the brake pad 20 is loaded into the calibrationmachine 100, the angle θ between the actuator 130 and the surface 36 ofthe friction material 24 may be verified and/or adjusted such that thepressure is applied at the correct angle to ensure that the correctnormal and shear forces are applied to the brake pad 20. Periodically,the actuator 130 and pressure sensor in the load pin 144 may be testedto verify that the pressure measured by the load pin 144 is equal to thepressure output by the actuator 130. For example, the calibrationmachine 100 may have a load cell (e.g., in addition to the pressuresensor in the load pin 144), or can be used with “dummy” brake pads(e.g., test units that are similarly shaped to a brake pad and thatincorporate one or more load cells), that provides absolute referencepressure measurements which is used to corroborate the pressure outputby the actuator 130 and the pressure measured by the load pin 144. Inoperation, the actuator 130 may apply test pressures to the load celland the pressure measurements from the pressure sensor in the load pin144 are compared to the pressure measurements of the load cell to verifythat the load pin 144 accurately measures pressure. Similarly, themeasurements from the load cell may be compared to actuator pressureindicators such as hydraulic pressure, for example, to verify that theactuator 130 is outputting the precise amount of pressure. Thecalibration machine 100 may be tested periodically to ensure that theprecise amount of pressure is being applied to the brake pads during thecalibration data determining process 200.

In some configurations, the brake pads 20 may have an on-board processorand memory. Accordingly, the calibration machine 100 may be configuredto determine calibration data such that the on-board processor of thebrake pads 20 may be calibrated using the calibration data. In someembodiments, each brake pad 20 is calibrated such that the output ofpressure sensors between substantially identically manufactured brakepads (e.g., same type and/or model) is substantially identical.

Another Example Calibration Machine

FIG. 7 illustrates another embodiment of a calibration machine 300. Incontrast to the calibration machine 100 in FIGS. 4A, 4B and 5, thecalibration machine 300 includes a dual actuator arrangement such thatthe normal forces and shear forces are applied by separate actuators. Insome embodiments, the normal force is applied by a first actuator andthe shear force is applied by a second actuator. For the sake ofbrevity, the following disclosure will discuss features not alreadydescribed in the above disclosure. The calibration machine 300 caninclude any of the features of the calibration machine 100.

The calibration machine 300 comprises a normal force actuator 130A thatis positioned substantially perpendicular to the brake pad 20 and ashear force actuator 130B that is positioned substantially parallel tothe brake pad 20. The normal force actuator 130A is positionedsubstantially parallel to a normal force direction of the brake rotorcontacting surface 36 of the friction material 24 of the brake pad 20.The shear force actuator 130B is positioned substantially parallel to ashear force direction of the brake rotor contacting surface 36 of thefriction material 24 of the brake pad 20. Accordingly, the normal forceactuator 130A applies a normal force to the brake pad 20 and the shearforce actuator 130B applies a shear or tangential force to the brake pad20. As discussed above, other types of actuators are contemplated, suchas hydraulically- or pneumatically-actuated pistons.

In the illustrated configuration, the normal and shear force actuators130A, 130B are comprised of electromechanical actuators. Accordingly,the normal and shear force actuators 130A, 130B are powered by electricmotors 138 which are individually controlled by a controller (notshown). Accordingly, the normal and shear force actuators 130A, 130B arecapable of being controlled and actuated independently such that thenormal and shear forces applied to the brake pad 20 may be individuallyadjusted.

The ends of each of the normal and shear force actuators 130A, 130B areattached to the pressure plates 140A, 140B by hubs 142A, 142B,respectively. In some embodiments, the pressure plates 140A, 140B areattached to the end of the rod 134 of each actuator 130A, 130B by hubs142A, 142B. The hubs 142A, 142B may be attached to the actuators 130A,130B by load pins 144. The load pins 144 allow rotation of the hubs142A, 142B relative to the actuators 130A, 130B. In some embodiments,the load pins 144 are configured to allow minimal adjustment of thepressure plates 140A, 140B and/or to ensure a good uniformity of theapplied pressure from the pressure plates 140A, 140B to the frictionmaterial surface of the braking pad.

In the illustrated configuration, the pressure plates 140A, 140B are notfixed to each other. Rather, the pressure plate 140B contacts andpresses against the pressure plate 140A. In some embodiments, a bottomsurface of the pressure plate 140A (e.g., a surface opposite the normalforce actuator 130A) contacts the surface 36 of the friction material 24such that the normal force is generally uniformly distributed across thesurface 36 of the friction material 24. Preferably, the pressure plate140A contacts substantially the entire upper surface 36 of the frictionmaterial 24. The shear force actuator 130B extends such that thepressure plate 140B contacts a lateral perimeter portion of the pressureplate 140A (e.g., a surface of the pressure plate 140A that isperpendicular to the normal force direction). The shear force actuator130B can extend such that the pressure plate 140B presses against thepressure plate 140A. Accordingly, a shear force is applied to thefriction material 24 of the brake pad 20 via the pressure plate 140Bapplying a force to the pressure plate 140A in a direction perpendicularto the normal force.

In some embodiments, the separate normal and shear force actuators 130A,130B enables the calibration machine 300 to conduct quality controltesting. For example, in addition to determining calibration data, thecalibration machine 300 is capable of conducting compressibility testingon the brake pad 20. As previously discussed, compressibility testingcan test for defects in the brake pad 20 created during themanufacturing process. In some implementations, the normal forceactuator applies a normal force onto the brake pad 20 to measure thevariation in thickness of the friction material 24 as a function of thepressure applied. In certain embodiments, only a normal force is appliedto the brake pad 20 and/or no shear force is applied with the actuator130B. As mentioned above, testing the compressibility of the brake pad20 can be an important parameter for validating the production of thebrake pad, such as for validating that the heat-treatment and/or curingprocess was proper. In some implementations, the compressibility isperformed with a laser unit. The laser unit can be placed on thepressure plate 140 on the side opposite of the shear force piston tomeasure, for instance, interferometrically the distance variation as afunction of the applied pressure (compressibility).

In some embodiments, separate normal and shear force actuators 130A,130B also enables the normal and shear forces to be individually variedduring the calibration data determination process. In some embodiments,in contrast to a single actuator arrangement, the shear force may beincreased or decreased without varying the normal force (or vice versa)and/or without requiring adjustment of the angle of the actuator.

Another Example Calibration Machine

FIGS. 8-13 illustrate another calibration machine 400. The calibrationmachine 400 can be a modified version of the calibration machine 300.The calibration machine 400 can include any feature of the calibrationmachine 100 and/or the calibration machine 300. In some embodiments, thecalibration machine 400 is mountable on surfaces that are slightlyuneven (e.g., on surfaces that are not perfectly level). As shown inFIGS. 8 and 9, the calibration machine 400 has an actuator angleadjustment mechanism 310 that allows the angles α and β of the normalforce actuator 130A to be adjusted relative to the direction of thesupport column 150, which is perpendicular to a surface of the base 110.Accordingly, the actuator angle adjustment mechanism 310 allows thenormal force actuator 130A to be adjusted, such as to account for agrade of the surface on which the calibration machine 400 is mounted.For the sake of brevity, the following disclosure will discuss featuresnot already described in the above disclosure.

FIGS. 8-11 illustrate an example of the actuator angle adjustmentmechanism 310. In various embodiments, the mechanism 310 allows theangle α of the normal force actuator 130A to be adjusted in the relativeto the direction of the support column 150. As shown, the calibrationmachine 300 has support columns 150 supported by a base 110. The supportcolumns 150 support opposing ends of a support beam 152. The normalforce actuator 130A is attached to actuator mounting supports 312 onopposing sides. The actuator mounting supports 312 can be planar platesformed from a rigid material such as metal. An upper end of the normalforce actuator 130A can be attached to the actuator mounting supports312 on opposing sides by upper journal ends 320. In some embodiments,each upper journal ends 320 may be received within a bearing 322 housedin the actuator mounting supports 312. The upper journal ends 320 canengage the bearings 322 to allow rotation of the normal force actuator130A about the upper journal ends 322. In some embodiments, the bearings322 comprise roller bearings, but may include other types of frictionreducing mechanisms.

A lower end of the normal force actuator 130A is attached to theactuator mounting supports 312 on opposing sides by lower journal ends324. Each lower journal end 324 may be received within a slot 326 in theactuator mounting supports 312. The lower journal ends 320 have adiameter that is similar to the width of the slot 326. However, the slot326 has a length that is greater than the diameter of the lower journalends 320. Accordingly, the lower journal ends 320 may slide within theslot 326 along the length of the slot 326. Sliding of the lower journalends 320 within the slot 326 allows the angle of the normal forceactuator 130A to be adjusted relative to the direction of the supportcolumn 152. In some embodiments, the slot 326 has a length that allowsat least 3 degrees of adjustment of the normal force actuator 130A. Theposition of the lower journal ends 320 within the slot 326 may besecured by an adjustment bolt 328 and a biasing spring 330. In someembodiments, the adjustment bolt 328 may engage one side of the lowerjournal end 320 while a biasing spring 330 presses against the opposingside of the lower journal end 320 such that the position of the lowerjournal ends 320 within the slot 326 is fixed. In some variants,adjustment bolts may be positioned and engage opposing sides of thelower journal end 320 such that the position of the lower journal ends320 within the slot 326 is fixed.

FIGS. 9 and 11 illustrate the actuator angle adjustment mechanism 310that allows the angle β of the normal force actuator 130A to be adjustedrelative to the direction of the support column 152. As shown, theactuator mounting supports 312 are supported by the support beam 152 byadjustment studs 314. A first end of each adjustment stud 314 is engagedwith the support beam 152. A second end of each adjustment stud 314 isengaged to the support beam 152. The studs 314 can be threaded andcomprise threaded rods or bolts. In some embodiments, rotation of thestuds 314 increase or decrease the distance between the support beam 152and the actuator mounting supports 312. As such, the distance betweenthe support beam 152 and the actuator mounting supports 312 at opposingends of the normal force actuator 130A may be varied such that the angleof the normal force actuators 130A may be adjusted relative to the base110.

FIG. 12 is a close-up cross-sectional side view of the calibrationmachine 400 in which the pressure plates 140A, 140B are engaging thebrake pad 20. As shown, the brake pad 20 is secured within the brake padretainer 120 and the connector 170 is connected to the connector 28 ofthe brake pad 20. The connector 170 can be connected to a cable 172 suchthat the signals from the pressure sensors 26 in the brake pad 20 can berouted to and received by the controller (not shown). In the illustratedconfigurations, the load pins 144 for each of the hubs 142A, 142B havebearings 146A, 146B. The bearings 146A, 146B reduce the friction betweenthe load pins 144 and the hubs 142A, 142B which prevent the unevenapplication of force onto the brake pad 20. In the illustratedconfiguration, the bearings 146A, 146B are comprised of ball bearingsbut may include other types of bearing and friction reducing mechanisms.In various embodiments, when the normal force actuator 130A is adjustedrelative to the direction of the support column 152, the bearings 146A,146B allow rotation of the hubs 142A, 142B and the pressure plates 140A,140B to accommodate for a difference in angle between a frictionmaterial engagement surface of the pressure plate 140A and the surface36 of the friction material 24 of the brake pad 20. In certainimplementations, the bearings 146A, 146B allow the pressure plates 140A,140B to rotate relative to the hubs 142A, 142B and to substantiallyuniformly engage the friction material 24 of the brake pad 20 when theangle of the normal force actuator 130A is adjusted relative to thedirection of the support column 152. In some embodiments, the bearings146A, 146B are placed on the actuator hub joining the actuator with therespective pressure plates 140A, 140B. The bearings 146A, 146B can allowminimal adjustment and/or can ensure a substantial uniformity of theapplied pressure to the friction material surface of the brake pad 20.In some embodiments, one or both of the bearings 146A, 146B is used toremove from the shear forces any contribution coming from the actuatoror friction between the plates 140A, 140B.

As shown in FIG. 13, the calibration machine 400 can be enclosed forsafety, such as in a cage 184. For example, the calibration machine 400can be surrounded by the cage 184 on at least 4 sides. As shown, thecalibration machine 400 can include a control panel 186, which caninclude the controller 160. The cage 184 can include a screen 188 thatdisplays operational information about the calibration machine, such asthe applied pressure, time, sensor readings, etc. The cage 184 includesone or more doors 190 that are used to open and close the cage 184 toallow loading and unloading of the brake pad 20, as well as closing thecage 184 for the calibration testing. As shown, in some embodiments, thecage 184 houses the compressor 136.

An Example Torque-Based Calibration Machine

Certain embodiments of this disclosure are configured to apply an actualtorque to the brake pad, rather than simulating a torque with a shearforce. Applying an actual torque to the brake pad can enable thecalibration machine to more closely simulate (e.g., be substantiallyidentical to) the forces that the brake pad 20 experiences when thebrake pad 20 is pressed against a spinning brake rotor of a vehicle.This can increase the accuracy of the calibration data provided by thecalibration machine.

FIG. 14 illustrates an example of a torque-based calibration machine500. In various embodiments, the calibration machine 500 is configuredto apply a normal force and a torque to the friction material 24 of asensorized brake pad 20. As illustrated, the machine 500 can include afixture or base 110, a brake pad retainer 120, and support columns 150.The machine 500 can include a normal force actuator 130 (e.g., a piston)and an actuator motor 138 (e.g., an electric motor). The actuator motor138 may comprise an electromechanical actuator such as an endless screwrotated by the actuator motor 138, however a variety of other mechanicaland/or electromechanical mechanisms may be used. Some embodimentsinclude non-linear actuators. The actuator motor 138 can drive thenormal force actuator 130 to apply a normal force to the frictionmaterial 24 of the brake pad 20. The actuator motor 138 can becontrolled and actuated by the controller. The normal force actuator 130and the actuator motor 138 can be comprised in a normal force assemblyof the machine 500.

The normal force actuator 130 can press the brake pad 20 against aplaten 520, such as a disk. The platen 520 can be configured to at leastpartially rotate. In some embodiments, a motor 530 rotates and/orapplies a torque to the platen 520. As illustrated, in certainimplementations, the platen 520 is coupled to an axle 532, which iscoupled to a gear reduction mechanism 534, which is coupled to the motor530. The motor 530 can be controlled by the controller. In someembodiments, the motor 530 applies the torque to the platen 520 afterthe normal force actuator 130 has pressed the brake pad 20 against theplaten 520. In certain variants, the frictional force between the brakepad 20 and the platen 520 can inhibit or prevent the platen 520 fromrotating relative to the brake pad 20. The platen 520 and the motor 530can be comprised in a torque assembly of the machine 500.

In some embodiments, the machine 500 includes a sensor, such as a shearload cell or a torque sensor. For example, the axle 532 may comprise thesensor. The sensor can be configured to detect the torque being appliedto the platen 520, such as during some or all of the calibration datadetermining process 200. Certain embodiments include a sensor, such as aload cell, for detecting the normal force being applied by the normalforce actuator 130. Several embodiments include a normal force sensorand a torque or shear force sensor. As previously described, the brakepad 20 can include normal and/or shear sensors.

As mentioned above, the machine 500 can include the gear reductionmechanism 534. In some embodiments, the gear reduction mechanism 534changes (e.g., increases) the torque that is output by the drive motor530. This can enable the calibration machine 500 to apply torque to theplaten 520 without being limited by the torque capacity or limits of thedrive motor 530. The gear reduction mechanism 534 may comprise, forexample, a planetary gearset that multiplies the torque that is outputby the drive motor 530 by a gear ratio provided by the planetarygearset. The drive motor 530 is not limiting and other torque generatingmechanisms may be used. For example, in other configurations, the torquemay be applied to the platen 520 by a linear actuator that rotates theaxle 532 via lever arm.

The platen 520 can be configured to simulate (e.g., be substantiallyidentical to) the brake rotor that the brake pad 20 would contact wheninstalled on the vehicle. For example, the platen 520 can be made of thesame material as and/or have a coefficient of friction that is about thesame as the brake rotor. In some implementations, the platen 520 isformed from steel, cast iron, or another metal. The platen 520 may beremovable from the calibration machine 500, such as by being unsecuredfrom the base 110. Removability can allow the platen 520 to be replacedwhen worn, or to be interchanged with a different platen 520 thatcorresponds to a different model or type of brake rotor that the brakepad 20 is to be used with when installed on a vehicle. This enables thecalibration machine 500 to generate calibration data for a variety ofbrake pads 20 with a variety of brake rotors.

Similar to the previous discussion, the brake pad 20 can be retained andsecured within the brake pad retainer 120. The brake pad 20 can beconnected to the controller via a connector (not shown) within the brakepad retainer 120. Data from the pressure sensors 26 of the brake pad 20can be received by the controller. The brake pad retainer 120 may beconnected to the normal force actuator 130 by an adjustment mechanism540. This can, in some embodiments, allow the orientation of the brakepad retainer 120 relative to the platen 520 to be adjusted such that thebrake pad 20 contacts the platen 520 substantially square and/or evenlyacross the surface of the friction material 24. The adjustment mechanism540 can comprise, for example, a lockable spherical bearing or the like.In some configurations, the adjustment mechanism 540 can include thenormal force sensor. As previously discussed, the brake pad retainer 120can include a laser unit to measure the compressibility of the brake pad20.

During the calibration data determining process 200, the normal forceactuator 130 presses the brake pad 20 against the platen 520. Thefriction material 24 of the brake pad 20 contacts and is pressed againstthe platen 520 such that a normal force is applied to the platen 520.The platen 520 is supported by the fixture 110 on a side opposite of thebrake pad 20 such that the platen 520 is sandwiched between the frictionmaterial 24 of the brake pad 20 and the fixture 110 when the normalforce is applied to the brake pad 20. During a portion of the timeduring which the normal force is applied, the drive motor 530 applies atorque to the platen 520, thereby applying a shear force to the frictionmaterial 24 of the brake pad 20 while the normal force is applied.During at least this time, data from the sensors of the brake pad 20 canbe received by the controller for use in producing the calibration datafor that brake pad.

In some implementations, during some or all of the calibration datadetermining process 200, the platen 520 is held substantially stationary(relative to the brake pad 20 and/or the actuator 130) by a frictionalengagement between the brake pad 20. In certain variants, the platen 520is held substantially stationary when the ratio of the shear force andthe normal force is less than the static friction coefficient μ of thebrake pad 20. This is expressed by the following:

$\frac{F_{t}}{F_{N}} < \mu_{s}$

Where:

μ_(s)=the static friction coefficient;

F_(t)=the shear or tangential force;

F_(N)=the normal force; and

The shear force F_(t) may be derived from the following equation:

$F_{t} = \frac{\tau}{2R}$

Where:

τ=the torque applied to the platen 520; and

R=the effective radius of the brake pad 20 relative to the platen 520.

Preferably, the normal force actuator 130 can apply a normal force orpressure, for example, within the range of 1 to 180 bars, which issimilar to the range of pressures applied to the brake pad 20 by thebrake caliper during a braking application. The drive motor 530 via thegear reduction mechanism 534 may apply a torque, such as at least aboutfor example, within a range of 6,000 Nm to 10,000 Nm, which is similarto the range of braking torque applied experienced by the brake pad 20during an emergency braking application.

Certain Terminology

Although certain calibration machines, systems, and processes have beendisclosed in the context of certain example embodiments, it will beunderstood by those skilled in the art that the scope of this disclosureextends beyond the specifically disclosed embodiments to otheralternative embodiments and/or uses of the embodiments and certainmodifications and equivalents thereof. Use with any structure isexpressly within the scope of this invention. Various features andaspects of the disclosed embodiments can be combined with or substitutedfor one another in order to form varying modes of the assembly. Thescope of this disclosure should not be limited by the particulardisclosed embodiments described herein.

Certain features that are described in this disclosure in the context ofseparate implementations can also be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation can also be implemented inmultiple implementations separately or in any suitable subcombination.Moreover, although features may be described above as acting in certaincombinations, one or more features from a claimed combination can, insome cases, be excised from the combination, and the combination may beclaimed as any subcombination or variation of any subcombination.

Terms of orientation used herein, such as “top,” “bottom,” “proximal,”“distal,” “longitudinal,” “lateral,” and “end” are used in the contextof the illustrated embodiment. However, the present disclosure shouldnot be limited to the illustrated orientation. Indeed, otherorientations are possible and are within the scope of this disclosure.Terms relating to circular shapes as used herein, such as diameter orradius, should be understood not to require perfect circular structures,but rather should be applied to any suitable structure with across-sectional region that can be measured from side-to-side. Termsrelating to shapes generally, such as “circular” or “cylindrical” or“semi-circular” or “semi-cylindrical” or any related or similar terms,are not required to conform strictly to the mathematical definitions ofcircles or cylinders or other structures, but can encompass structuresthat are reasonably close approximations.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include or do not include, certain features, elements,and/or steps. Thus, such conditional language is not generally intendedto imply that features, elements, and/or steps are in any way requiredfor one or more embodiments.

Conjunctive language, such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to convey that an item, term, etc. may beeither X, Y, or Z. Thus, such conjunctive language is not generallyintended to imply that certain embodiments require the presence of atleast one of X, at least one of Y, and at least one of Z.

The terms “approximately,” “about,” and “substantially” as used hereinrepresent an amount close to the stated amount that still performs adesired function or achieves a desired result. For example, in someembodiments, as the context may dictate, the terms “approximately”,“about”, and “substantially” may refer to an amount that is within lessthan or equal to 10% of the stated amount. The term “generally” as usedherein represents a value, amount, or characteristic that predominantlyincludes or tends toward a particular value, amount, or characteristic.As an example, in certain embodiments, as the context may dictate, theterm “generally parallel” can refer to something that departs fromexactly parallel by less than or equal to 20 degrees.

Some embodiments have been described in connection with the accompanyingdrawings. The figures are to scale, but such scale should not belimiting, since dimensions and proportions other than what are shown arecontemplated and are within the scope of the disclosed invention.Distances, angles, etc. are merely illustrative and do not necessarilybear an exact relationship to actual dimensions and layout of thedevices illustrated. Components can be added, removed, and/orrearranged. Further, the disclosure herein of any particular feature,aspect, method, property, characteristic, quality, attribute, element,or the like in connection with various embodiments can be used in allother embodiments set forth herein. Additionally, it will be recognizedthat any methods described herein may be practiced using any devicesuitable for performing the recited steps.

SUMMARY

Various illustrative embodiments of calibration machines, systems, andmethods have been disclosed. Although the machines, systems, and methodshave been disclosed in the context of those embodiments, this disclosureextends beyond the specifically disclosed embodiments to otheralternative embodiments and/or other uses of the embodiments, as well asto certain modifications and equivalents thereof. This disclosureexpressly contemplates that various features and aspects of thedisclosed embodiments can be combined with, or substituted for, oneanother. Accordingly, the scope of this disclosure should not be limitedby the particular disclosed embodiments described above, but should bedetermined only by a fair reading of the claims that follow as well astheir full scope of equivalents.

The following is claimed:
 1. A method for determining calibration datafor a sensorized brake pad that comprises force sensors configured tooutput signals in response to force applied to the sensorized brake pad,the method comprising: retaining the sensorized brake pad in a fixturein a calibration machine, the calibration machine external to a vehicle;controlling the calibration machine to adjust an angle θ between a forcedirection of an actuator of the calibration machine and a plane formedby a surface of a friction element of the sensorized brake pad, theadjusted angle θ being non-orthogonal; applying, with the actuator ofthe calibration machine, force to the sensorized brake pad in the forcedirection to apply both normal and shear forces to the surface of thefriction element; receiving signals outputted from the force sensorswhile the force is being applied to the sensorized brake pad;determining calibration data for the sensorized brake pad based on thesignals; storing the calibration data into a memory; and providing thecalibration data to a user for installing in a controller of a vehicleon which the sensorized brake pad is installed.
 2. The method of claim1, further comprising associating an optical code with the calibrationdata of the sensorized brake pad, and providing the optical code withthe brake pad.
 3. The method of claim 2, wherein the optical codecomprises a QR code.
 4. The method of claim 2, further comprisingreceiving a request for the calibration data of the brake pad inresponse to scanning of the optical code.
 5. The method of claim 1further comprising applying, with a second actuator of the calibrationmachine, a force to the sensorized brake pad in a force direction of thesecond actuator.
 6. The method of claim 5 wherein the second forcedirection is tangential to the surface of the friction element of thesensorized brake pad.
 7. The method of claim 1, wherein a ratio of theshear force to the normal force is less than a static coefficient offriction of a friction element of the brake pad.
 8. The method of claim1, wherein the wherein the ratio of the shear force over the normalforce is equal to about tan θ.
 9. The method of claim 1, furthercomprising monitoring a thickness of friction material of the brake padduring the applying of the force.
 10. The method of claim 1, wherein thestoring of the calibration data into memory further comprises storingthe calibration data into memory on-board the sensorized brake pad. 11.The method of claim 1, further comprising automatically moving anelectrical connector of the calibration machine into engagement with amating connector of the sensorized brake pad.
 12. The method of claim 1wherein the force sensors comprise one or more normal sensors and one ormore shear sensors.
 13. The method of claim 1 further comprisingapplying, by actuating a torque assembly of the calibration machine, atorque to the surface of the friction element.
 14. A method fordetermining calibration data for a sensorized brake pad that comprisesone or more force sensors configured to output signals in response toforce applied to the sensorized brake pad, the method comprising:retaining the sensorized brake pad in a calibration machine, thecalibration machine external to a vehicle; applying, with a firstactuator of the calibration machine, force to the sensorized brake padin a force direction of the first actuator, a first angle formed betweenthe force direction of the first actuator and a plane formed by asurface of a friction element of the sensorized brake pad; applying,with a second actuator of the calibration machine, force to thesensorized brake pad in a force direction of the second actuator, asecond angle formed between the force direction of the second actuatorand the surface of the friction element, the second angle different thanthe first angle; receiving signals outputted from the one or more forcesensors while the force is being applied to the sensorized brake pad bythe first actuator and while the force is being applied to thesensorized brake pad by the second actuator; determining calibrationdata for the sensorized brake pad based on the signals; and storing thecalibration data into a memory.
 15. The method of claim 14, furthercomprising electronically accessing the calibration data with aprocessing unit of a vehicle on which the brake pad is installed. 16.The method of claim 15 further comprising, with the processing unit,electronically accessing an identifier associated with the brake pad,and wherein said electronically accessing the calibration data comprisesaccessing the calibration using the identifier.
 17. The method of claim14, further comprising: controlling the calibration machine to adjustthe first angle; and applying, with the first actuator of thecalibration machine, force to the sensorized brake pad in an adjustedforce direction of the first actuator at the adjusted first angle. 18.The method of claim 17, wherein the second angle is tangential to thesurface of the friction element.
 19. The method of claim 14 wherein thememory comprises an on-board memory of the brake pad.
 20. The method ofclaim 14, further comprising installing the brake pad on the vehicle.21. The method of claim 14, further comprising, with a processing unitof a vehicle on which the brake pad is installed, using the calibrationdata to process signals outputted from the one or more force sensors.22. The method of claim 14 further comprising modifying, with thecalibration data, braking control programming in a processing unit of avehicle on which the brake pad is installed.
 23. The method of claim 14further comprising using the calibration data to calibrate a brakingsystem of a vehicle on which the brake pad is installed.
 24. The methodof claim 14 wherein the one or more force sensors comprise one or morenormal sensors and one or more shear sensors.
 25. The method of claim14, wherein the first angle is normal to the surface of the frictionelement and the second angle is tangential to the surface of thefriction element.